AIM 1. Establish a multicenter Vasculitis clinical Research Network (VCRN) to foster and facilitate clinical investigation in the inflammatory vasculitides. The 4 major US vasculitis centers (Boston University, Cleveland Clinic, Johns Hopkins, and Mayo Clinic) will combine their clinical and research expertise with the resources of the General Clinical Research Centers at each site to form the core of the Network. Additionally, the combined strengths of several domestic and foreign secondary centers will be incorporated into the Network. The VCRN would serve as the focal point for vasculitis research in the United States and internationally for both clinical investigators and patients. To achieve this aim, the following activities are proposed: 1.1 Develop a clinical data repository in collaboration with other Rare Disease Clinical Research Networks and the Rare Disease Data and Technology Coordinating Center. 1.2 Build a vasculitis clinical specimen bank for storage of serum, plasma, DNA and tissue samples linked to the clinical data repository. 1.3 Enact a national recruitment program in cooperation with various vasculitis patient advocacy groups. 1.4 Utilize the extensive resources of the General Clinical Research Centers at each Primary Network Site AIM 2. Conduct a series of related longitudinal studies of novel biomarkers of vasculitis disease activity. Utilizing the VCRN Clinical Data Repository and Clinical Specimen Bank and in coordination with biostatistical support from the Data and Technology Coordinating Center, the VCRN Biomarkers Project will use several promising techniques to develop new markers of disease activity including: 2.1 Proteomics 2.2 Molecular Markers of Oxidative Stress and Inflammation 2.3 Additionally, this program will be established in a fashion that would easily allow for testing of future novel biomarkers by investigators both within and beyond the Network. AIM 3. Utilize the VCRN and patient base to conduct Phase I and II clinical trials within the proposed grant period and create the infrastructure to greatly facilitate the design and performance of other future trials. AIM 4. Establish the Vasculitis Clinical Investigator Fellowship as a core mission on the VCRN to provide a mechanism to support, train, and mentor fellows interested in establishing academic careers focused on vasculitis research. This aim will address the pressing need in academic medicine for the training and retaining of patient oriented clinical investigators. AIM 5. Build and contribute to an electronic website resource with substantive content for clinicians, researchers, and patients.